1. Technical Field of the Invention
The present invention relates to form factor designs for providing storage devices as a Printed Board Assembly on a backplane and, more particularly, to a storage card design that is compatible with the Compact Peripheral Component Interconnect (CPCI) standard. Preferably, the card design is implemented in a subrack of a network element (e.g., a Next Generation Signaling Transfer Point (STP)) disposed in a Signaling System No. 7 (SS7) network.
2. Description of Related Art
The exponential increase in the number of local telephone lines, mobile subscribers, pages, fax machines, and other data devices, e.g., computers, Information Appliances, etc., coupled with deregulation that is occurring worldwide today is driving demand for small form factor, high capacity STPs which must be easy to maintain, provide full SS7 functionality with so-called xe2x80x9cfive ninesxe2x80x9d operational availability (i.e., 99.999% uptime), and provide the capability to support future functionality or features as the need arises. Further, as subscriber demand for more service options proliferates, an evolution is taking place in the telecommunications industry to integrate Intelligent Network (IN)-capable Service Control Point (SCP) functionality within STP nodes.
While it is generally expected that a single platform that supports large-database, high-transaction IN services as well as high-capacity packet switching (hereinafter referred to as a signaling server platform) will reduce equipment costs, reduce network facility costs and other associated costs while increasing economic efficiency, those skilled in the art should readily recognize that several difficulties must be overcome in order to integrate the requisite functionalities into a suitable network element that satisfies the stringent performance criteria required of telecommunications equipment. Daunting challenges arise in designing a compact enough form factor that is efficiently scalable, ruggedized, and modularized for easy maintenance, yet must house an extraordinary constellation of complex electronic circuitry, e.g., processors, control components, timing modules, I/O, line interface cards which couple to telephony networks, etc., that is typically required for achieving the necessary network element functionality. Whereas the electronic components may themselves be miniaturized and modularized into cards or boards that can be interconnected via suitable backplanes, implementing the requisite functionality within a stringent form factor poses many obstacles.
It should be apparent to those skilled in the art that because backplanes typically have a rigid slot budget, i.e., the number of slots available for connecting cards thereto, consuming as few slots as possible while still accomplishing applicable functional objectives gives rise to a significant design challenge. This is particularly so in the context of providing high-speed media storage in the form of cards required to be disposed on a backplane. Not only is the backplane""s slot budget is a major concern, the form factor of the storage devices itself gives rise to additional complications. Typically, the size of such devices, e.g., disk drives, tape drives, etc., is bulky in relation to the available card space, and where multiple storage devices are required, such functionality is conventionally accomplished by providing a storage card assembly that is about three or more slots in width.
Further, conventional backplane arrangements for supporting storage I/O interfaces are beset with numerous additional deficiencies and drawbacks as well. In the existing solutions, for example, the bus slot that is to receive a storage I/O card is hardwired to accept only that particular type of storage device and typically will not work with other storage devices without extensive modifications which may include both electrical and mechanical aspects. That is, a bus slot designed for a tape drive card will not accept a disk drive card and vice versa.
Moreover, if it is required for some reason that a storage bus slot be used not for storage cards but for some other functionality, e.g., processing element functionality, the existing backplanes cannot accommodate such requirements. Thus, once a bus slot is formed for a particular purpose and device, there is very little that can be done with the arrangement if future needs require replacement or a change in the use of the slot. Consequently, adaptability of a system having such conventional bus slot arrangements is severely impacted.
Accordingly, the present invention is directed to a storage card module that is no wider than two Compact Peripheral Component Interconnect (CPCI) slots on a backplane yet advantageously provides more than one high speed storage device on a card substrate. The storage card module comprises a printed circuit board (PCB) provided as a front panel card in accordance with the CPCI bus standard, wherein the PCB supports traces that extend from the PCB""s card connector that is matched to at least one backplane connector disposed on the CPCI backplane. The backplane connector is coupled to an input/output (I/O) bus interface which preferably comprises a Small Computer System Interface (SCSI) bus interface.
In accordance with the teachings of the present invention, a first storage device is positioned on the PCB with a first predetermined spacing disposed therebetween. Similarly, a second storage device is also positioned on the PCB with a second predetermined spacing disposed therebetween. At least one low profile connector is disposed in each of the first and second predetermined spacings, wherein the low profile connector(s) is (are) coupled to the card connector via at least a portion of the traces supported by the PCB. In a preferred exemplary embodiment, the traces are buried in the PCB substrate and extend from the card connector to the low profile connectors. A flexible ribbon cable is disposed between the low profile connector(s) and a corresponding storage device, i.e., the disk or tape drive, for providing an electrical path therebetween. Also disposed in the predetermined spacing are a pair of low profile power connectors for supplying power to the SCSI drives, which low profile power connectors are also coupled to the card connector via at least a portion of the buried traces.
In a presently preferred exemplary embodiment of the present invention, the tape drive comprises an 8-bit fast SCSI tape drive with a 50-pin interface that is coupled to a single 50-pin low profile connector via an unbranched ribbon cable. The disk drive preferably comprises a 16-bit fast-wide SCSI disk drive with a 68-pin interface. Accordingly, two low profile connectors each having 34 pins are provided such that a Y-forked flexible ribbon cable connects the low profile connectors to the disk drive.